This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Small Leucine-Rich Repeat proteins (SLRPs) are a large group of glycoproteins with considerable medical applications in areas of wound healing, degenerative diseases and cancer. The proteoglycans usually exert their function through the binding of other proteins within the extra-cellular matrix. The unique structures of the protein cores of the SLRPs show a super helix of beta strands formed by the leucine repeats. Unique regions are capping the elongated molecules at both ends. The SLRPs are heavily glycosylated and difficult molecules to work with, both biochemically and for crystallization purposes. Few of these molecules are easily or readily available from bacterial expression systems. In an effort to understand the relationship between the structure and the biological function of these molecules we are pursuing crystal structures of all representative members of this family of proteoglycans. We have determined crystal structures of the protein cores of decorin and biglycan and also recently obtained diffraction quality crystals of lumican. A solution structure of decorin from small angle x-ray scattering was also obtained to verify some of the conclusions from the decorin crystal structure.